1. Field
The present disclosure relates generally to threaded members and, in particular, to locking mechanisms for threaded members. Still more particularly, the present disclosure relates to an apparatus and method for preventing rotational motion of an externally threaded member relative to one or more internally threaded members using a shape memory element.
2. Background
In certain systems and assemblies, threaded shafts, such as, for example, lead screws, are used to convert rotational motion into linear motion. For example, rotating a lead screw about a longitudinal axis through the lead screw relative to a nut engaged with the lead screw may cause translation of the nut in a direction along the axis relative to the lead screw. As one specific example, a lead screw in a milling machine may be rotated by a motor, which may drive a nut engaged with the lead screw in a direction along a longitudinal axis through the lead screw.
This type of movement mechanism may allow for precise control of the position of the nut. Further, with this type of movement mechanism, the thread pitch of the external thread of the lead screw and the thread pitch of the internal thread of the nut may be designed such that the nut moves relative to the lead screw according to selected mechanical requirements.
Depending on the implementation, rotation of the lead screw may result in translation of the nut or the lead screw relative to the other. In other examples, rotation of the nut around the lead screw may result in translation of the lead screw or the nut relative to the other.
In some cases, a mechanism that prevents the nut engaged with the lead screw from moving relative to the lead screw in response to vibration, movement of the assembly, and/or other factors may be desirable. For example, when a lead screw is used in a braking system, a mechanism for preventing the nut engaged with the lead screw from back driving may be required. However, a locking mechanism capable of preventing the relative rotation between a lead screw and a nut within selected tolerances may not be available. Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.